Lukas Lehner

Clinical Outcome of Patients with De Novo C1q-Binding Donor-Specific HLA Antibodies after Renal Transplantation.

Background De novo donor specific anti-HLA antibodies (dnDSA) may cause graft loss in renal transplant recipients. The capability to bind the complement may help to stratify the risk for inferior outcomes associated with dnDSA. We developed a modified C1q-binding assay and hypothesized that C1q-binding dnDSA could differentiate between indolent and harmful dnDSA causing antibody-mediated rejection (AMR) and graft loss. Methods We retrospectively identified 59 renal transplant recipients who developed dnDSA and had serum available and complete follow-up. All patients were analyzed for C1q-binding dnDSA at the time of dnDSA detection, and 1-year later or at time of AMR. AMR-positive patients were also tested 6 to 12 months before the event if IgG dnDSA was present. Results Thirty-seven of 59 dnDSA+ patients developed AMR during 5.9 ± 3.1 years follow-up. AMR-positive patients had more dnDSA with a significant higher frequency of class I, a higher frequency and a higher mean fluorescence intensity value of C1q+-dnDSA at all time-points. Death-censored AMR-free and allograft survivals were significantly lower in C1q+-dnDSA patients. In multivariate analysis, C1q+-dnDSA was an independent risk factor for AMR. Conclusions C1q-binding dnDSA is associated with inferior outcomes, yet not in all patients. Nevertheless, C1q+-dnDSA was shown to be an independent risk factor of AMR and graft loss and may be a useful tool to stratify the immunological risk for AMR.

The inferior impact of antibody-mediated rejection on the clinical outcome of kidney allografts that develop de novo thrombotic microangiopathy.

Antibody‐mediated rejection (AMR) can induce and develop thrombotic microangiopathy (TMA) in renal allografts. A definitive AMR (dAMR) co‐presents three diagnostic features. A suspicious AMR (sAMR) is designated when one of the three features is missing.

Need for optimized immunosuppression in elderly kidney transplant recipients

UNLABELLED The proportion of elderly kidney transplant candidates is increasing worldwide due to higher number of patients with end-stage renal disease in aging societies. ALLOCATION Accordingly, organ allocation policies in this population were adjusted in several countries. The European Senior Program is the most prominent example, where elderly patients (≥65years) receive elderly (≥65years) donor organs with acceptable results. IMMUNOSENESCENCE Because of age-dependent changes in the immune response and higher susceptibility to immunosuppressant side effects, outcomes in elderly patients are different compared to younger kidney transplant recipients. However, elderly patients do reject, especially poorly matched elderly donor organs. This warrants tailored immunosuppressive regimes with regard to the age-related changes of the immune system. SIDE EFFECTS Rejection therapies may have detrimental side effects in the seniors and are frequently leading to over-immunosuppression (malignancy and infections) in long-term therapy. It is hypothesized that after initial graft adaptation elderly patients may benefit from less immunosuppression in order to lower cancer risk and reduce infection rates and cardiovascular comorbidities. LACK OF DATA Current evidence on recommended standard immunosuppressive therapy was mainly derived from trials, where elderly patients were excluded or only a minority. In order to improve immunosuppressive therapy in elderly transplant recipients, current immunosuppressive regimes have to be re-investigated in this growing population. Up to date, only a few well-designed prospective studies were performed in elderly populations and demonstrate the need for effective immunosuppression in the first months after transplantation. CONCLUSION It is evident that novel treatment strategies and adequately powered prospective clinical trials are needed to establish time-adapted immunosuppressive regimens according to the needs of this vulnerable group of kidney transplant recipients.

Hyperlactatemia, Lactate Kinetics and Prediction of Citrate Accumulation in Critically Ill Patients Undergoing Continuous Renal Replacement Therapy With Regional Citrate Anticoagulation

Objectives: Citrate accumulation is a major complication of regional citrate anticoagulation during continuous renal replacement therapy. We studied the prediction of citrate accumulation during continuous veno-venous hemodialysis with regional citrate anticoagulation by initial lactate concentrations and lactate kinetics. Design: A retrospective follow-up analysis from a cohort of critically ill patients. Setting: Mixed medical-surgical ICUs at a university hospital. Patients: All adult patients with acute kidney injury and treated with regional citrate anticoagulation-continuous veno-venous hemodialysis during a 3-year period (n = 1,070) were included in this retrospective study and screened for metabolic signs of citrate accumulation. Interventions: None. Measurements and Main Results: The frequency of citrate accumulation during the first 48 hours of therapy was 2.26%. In patients with initial normal lactate (< 2.2 mmol/L), elevated lactate (≥ 2.2 to < 4 mmol/L), or severe hyperlactatemia (≥ 4 mmol/L), the frequency of citrate accumulation was 0.77%, 2.70%, and 6.33%, respectively. Receiver operating characteristics-area under the curve of initial lactate concentration was 0.789 for the prediction of citrate accumulation. Optimal cutoff from receiver operating characteristics (2.39 mmol/L) showed strong negative prediction (99.28%), but weak positive prediction (5.21%). The slope intercept of lactate kinetics over 48 hours was positive and significantly higher in patients with citrate accumulation compared to those without (+0.2 vs –0.006 mmol/L/hr; p < 0.001). In patients with initial severe hyperlactatemia (≥ 4 mmol/L), the median calculated lactate clearance at 6, 12, and 18 hours was 24.0%, 48.1%, and 59.4% in the nonaccumulation group. These clearance rates were significantly higher at each time-point compared to patients with citrate accumulation (–9.8%, –20.5%, and 2.3%, respectively; p < 0.001 for each time-point). The highest receiver operating characteristics-area under the curve for citrate accumulation was observed for 12-hour values of lactate clearance (area under the curve = 0.839; 95% CI, 0.751–0.927) with an optimal cut-off value of 24.3%. Conclusions: Risk of citrate accumulation during regional citrate anticoagulation in a well-selected cohort of patients is low even in case of initial severe hyperlactatemia. Lactate kinetics rather than initially elevated lactate concentration should be considered in assessing the risk of citrate accumulation.

Evaluation of adherence and tolerability of prolonged‐release tacrolimus (Advagraf™) in kidney transplant patients in Germany: A multicenter, noninterventional study

This study assessed adherence to prolonged‐release tacrolimus (PR‐T)‐based immunosuppression during routine maintenance of renal transplant recipients in Germany. Patients had received PR‐T for ≥1 month at inclusion. Data were collected during four visits (V): baseline (V1), 6 (V2), 12 (V3), and 18 (V4) months. Composite primary endpoint: nonadherence at V4, defined as self‐reported nonadherence on the Basel Assessment of Adherence with Immunosuppressive Medication Scale (BAASIS©), investigator‐rated nonadherence, and/or V4 tacrolimus trough level outside a predefined range. Secondary endpoints: individual BAASIS items, incidence of rejection, kidney function, and safety. Overall, 153 adult kidney recipients (mean [standard deviation] time post‐transplant 5.8 [4.6] years) were included. Nonadherence was high at V4 (67.7% [95% confidence interval 58.9%, 75.6%]). Medication‐taking adherence was 86.9% and 91.3% at V1 and V4, respectively; adherence to timing of medication intake was 58.2% and 58.3%, with little evidence of missed doses/drug holidays. Investigators rated adherence “good” in 85.6% of patients (V4). Two (1.3%) patients had acute rejection episodes. Kidney function remained stable (mean creatinine clearance, V1: 62.1 mL/min; V4: 65.3 mL/min). Investigators rated effectiveness of PR‐T as “very good”/“good” in 91.5% of patients. Most patients (94.7%) found PR‐T dosing more convenient than immediate‐release tacrolimus. PR‐T was well tolerated with high medication persistence.

Pharmacokinetics and Clinical Outcomes of Generic Tacrolimus (Hexal) Versus Branded Tacrolimus in De Novo Kidney Transplant Patients: A Multicenter, Randomized Trial

Background Scrupulous comparison of the pharmacokinetic and clinical characteristics of generic tacrolimus formulations versus the reference drug (Prograf) is essential. The pharmacokinetics of the Tacrolimus Hexal (TacHexal) formulation is similar to Prograf in stable renal transplant patients, but data in de novo patients are lacking. Methods De novo kidney transplant patients were randomized to generic tacrolimus (TacHexal) or Prograf in a 6-month open-label study. Results The primary end point, the dose-normalized area under the curve0-12h at month 1 posttransplant, was similar with TacHexal or Prograf; back-transformed geometric means of adjusted log-transformed values (analysis of variance) were 18.99 ng·h·L−1 (TacHexal) and 20.48 ng·h·L−1 (Prograf) (ratio, 1.08; 90% confidence interval, 0.84-1.38; P = 0.605). The dose-normalized peak concentration geometric means at month 1 was also comparable between treatments (ratio, 1.16; 90% confidence interval, 0.88-1.54; P = 0.377). There were no relevant differences in other pharmacokinetic parameters at month 1 or in area under the curve0-4h and trough concentration when measured at months 3 and 6. The adjusted change in mean estimated glomerular filtration rate from baseline to month 6 (Nankivell) was noninferior for TacHexal versus Prograf using observed values (47.7 vs 38.6 mL/min per 1.73 m2, P < 0.001) and was superior based on observed values (P = 0.044) but not using last observation-carried forward method. Rates of biopsy-proven acute rejection (5.7% vs 7.9%), adverse events, and serious adverse events were similar with TacHexal or Prograf. Conclusion Tacrolimus pharmacokinetics is similar with TacHexal and Prograf early after kidney transplantation. Efficacy and safety in this limited data set were comparable, with at least equivalent graft function under TacHexal.

Assessment of the Kidney Donor Profile Index in a European cohort

Background Recently, transplant societies have had to change their allocation policies to counter global organ shortages. However, strategies differ significantly and long-term outcomes and cross-regional applicability remain to be evaluated. Methods Therefore, we retrospectively analysed the Kidney Donor Profile Index (KDPI) of 987 adult kidney transplants at our centre using data from the Organ Procurement and Transplantation Network (OPTN) as a reference. Results In our cohort, the median KDPI was 66%, with a higher proportion of >85% KDPI kidneys compared with the US cohort (32.3% versus 9.2%). Among elderly patients (≥65 years of age), 62% received >95% KDPI kidneys, which were primarily allocated within the Eurotransplant Senior Program (ESP). After 10 years, the rate of death-censored graft survival was 70.5%. Recipients of >85% KDPI kidneys were significantly older, demonstrating higher mortality, poorer graft survival and lower estimated glomerular filtration rate. Patients receiving ≥99% KDPI kidneys had a satisfactory 5-year death-censored graft survival (72.9%). The 5-year survival rate of patients living with a functioning graft exceeded the matched OPTN data in the whole KDPI range, despite a higher proportion of elderly recipients. Multivariate analysis revealed KDPI as an independent risk factor for graft loss (hazard ratio 1.14/10%, P < 0.001), although C-statistics of 0.62 indicated limited discriminative ability for individuals. Conclusion The analysis demonstrated KDPI as a potentially useful tool for donor quality assessment in a European cohort. Most importantly, our analysis revealed acceptable outcomes even for very high KDPI kidneys.

Validation of the Living Kidney Donor Profile Index in a European cohort and comparison of long-term outcomes with US results

BACKGROUND Recently, a risk index for living donor kidney (LDK) transplantation [living kidney donor profile index (LKDPI)] was proposed to compare LDKs with each other and with deceased donor kidneys (DDKs). Until now, the LKDPI has not been validated externally. METHODS This long-term retrospective analysis included 1305 consecutive adult kidney transplant recipients who were transplanted 2000-16 in our centre. The Kidney Donor Profile Index (KDPI) was calculated in 889 DDKs and the LKDPI in 416 LDKs. Outcome was followed over a median of 6.5 years. RESULTS The median LKDPI was 17 and the median KDPI was 69, with a high proportion of donor kidneys with a very high KDPI (40% KDPI ≥ 80). Categorization of LDK into LKDPI quartiles (LKDPI -45-3, 3-17, 17-33, 33-90) revealed a significant difference in death-censored graft survival. Comparing corresponding subgroups of the LKDPI and KDPI (LKDPI/KDPI 0-20 or 20-40) showed comparable graft survival. A multivariate analysis adjusting for relevant recipient factors revealed the KDPI [hazard ratio (HR) 1.21; P < 0.001) and LKDPI (HR 1.15; P = 0.049) as significant independent predictors of graft loss. Time-to-event receiver operating characteristic analyses for graft survival demonstrated lower predictive discrimination of the LKDPI [area under the curve (AUC) 0.55] compared with the KDPI (AUC 0.66). The 10-year graft survival of LDK recipients was inferior in the USA compared with our centre (79% versus 84%). CONCLUSIONS These results provide external validation of the LKDPI to predict death-censored graft survival and confirm comparability of the LKDPI with the KDPI to discriminate post-transplant outcome.

Incidence of Infectious Disease and Malignancies After Rituximab Therapy in Kidney Transplant Recipients: Results From a Cohort in Germany

BACKGROUND Rituximab is frequently used in solid organ transplantation off-label, especially in patients with renal allografts. Few data are available on the safety aspects of solid organ transplant recipients receiving rituximab. There is a knowledge gap on long-term follow-up data, in particular on infectious complications. PATIENTS AND METHODS A retrospective observational registry study (German Registry on Autoimmune Diseases) comprising a total of 681 patients was conducted. The data of 63 adult kidney transplant recipients who received rituximab between 2006 and 2013 were used in this analysis. RESULTS Median follow-up was 42 (1-109) months. At least 1 severe infection occurred in 57% of patients. The median time between the first rituximab infusion and the first infection was 4 (1-48) months. Of the overall 88 infections, 74 were severe bacterial infections, 5 were severe viral infections, 3 were severe fungal infections, 2 were combined severe bacterial and fungal infections, and 4 were combined severe viral, fungal and bacterial infections. Seven patients died during the observational period, 2 of them due to infectious complications. In the observational period, 1 case of squamous cell carcinoma but no other malignancies were observed. CONCLUSION Consistent with previous data, a high incidence of infections was observed after rituximab treatment in kidney transplant recipients. Most infections occurred within 6 months after rituximab initiation. With more than 3 years of follow-up, we were able to document a low incidence of secondary malignancies after rituximab with only 1 case in our cohort.